PDEP-8 inplace keyword deprecation - implementation tracker issue (original) (raw)

Issue to track the progress of implementing the accepted PDEP-8: https://pandas.pydata.org/pdeps/0008-inplace-methods-in-pandas.html

Summary of the PDEP proposed changes:

• The inplace parameter will be removed from any method which can never update the
  underlying values of a pandas object inplace or which alters the shape of the object,
  and where the inplace=True option is only syntactic sugar for reassigning the result
  to the calling DataFrame/Series.
  • In practice, this are the methods drop, rename, rename_axis, reset_index, set_index, dropna drop_duplicates, sort_values, sort_index, eval, query
• The inplace parameter is kept for those methods that can
  modify the underlying values of a pandas object inplace, such as fillna or replace, and those methods will return the calling object (self), instead of the current None.
• With the introduction of Copy-on-Write (PDEP-7), users don't need the inplace keyword to avoid a copy of the data.

List of TODO items:

For 3.0:

• Start returning self instead of None for the methods that will keep the inplace keyword: PDEP-8 inplace: return self for inplace=True in methods that will keep the keyword #63195
• Announce the future deprecation and update documentation to already discourage usage of it (the user guide already does not mention it, but docstrings could use some update to discourage use / mention future deprecation)

For 3.1:

• Add actual deprecation warnings to the methods where we will remove the keyword in the future (4.0)